$ \left(\dfrac{9}{8}\right)^{-3}$
Solution: $= \left(\dfrac{8}{9}\right)^{3}$ $= \left(\dfrac{8}{9}\right)\cdot\left(\dfrac{8}{9}\right)\cdot \left(\dfrac{8}{9}\right)$ $= \dfrac{64}{81}\cdot\left(\dfrac{8}{9}\right)$ $= \dfrac{512}{729}$